When it comes to BIM implementation, the MEP sector faces a series of unique challenges. Here, Georg Hewelt – Product Manager for Trimble International (Germany) – explains how working in close consultation with clients influenced the development of Plancal nova to reflect MEP customers’ industry-specific experiences and provide a targeted solution to the issues they face when adopting BIM. Application of IFC files in file exchange and resulting requirements for BIM software developers. Although BIM has been integral to our discussions and development programme for a very long time, it’s only recently that we’ve recognised a rising interest among clients and potential clients in the MEP sector. For the first time, contractors and subcontractors are being confronted with a request from building owners to apply BIM in projects. However, at the moment its application is not yet set out as a contractual requirement and is more of an informal arrangement. Interest really is rising among all project stakeholders but there’s also uncertainty about how the implementation of BIM will change work flows and how software can help with all the new requirements they face now. These points demonstrate that there’s now a need for discussion and consultancy between us and our clients specifically within the MEP industry where specialist knowledge is key. In most cases, our communication and consultation with our customers focuses on the explanation of BIM as a work process while the software itself is just a tool within this. This approach and the excellent relationships it promotes with our customer base also means we benefit from honest and open feedback, again improving our bank of expert knowledge and enriching our understanding of the difficulties our individual market might encounter during the implementation of BIM.

Unique challenges facing the MEP sector

While architects usually work in building models they created themselves, MEP designers widely need to work on an existing model created by a third party. One of the biggest challenges they face are changes made to the model in response to the requirements of clients. Sometimes it’s just a door stop that has changed but sometimes entire installation voids are modified. As a result, whether the MEP designers need to rework their designs or not is also subject to change and the workload associated with it is variable. Also unique to the MEP sector is that the work-flow is essentially based on three different main aspects and equivalent modifications in the planning process. These are: • Essential areas for MEP installations (room layouts, ceiling heights, location of voids, risers, and plant rooms) • Designs essential for the thermal calculations such as heat loss and cooling (room layouts, wall constructions, thermal properties) • Designs essential for understanding and graphic design (dimensions, annotations, etc.)

First experiences with the implementation and use of BIM models

Both, our clients and ourselves, started with the idea that it is necessary to always import the entire building model from architects. Quickly it turned out that it is more desirable to import data floor by floor only if needed, as it is easier to track differences to previous versions of the project. Another conclusion that derived from early adopters is that there is a need to remove IFC classes that are not relevant for MEP designers in order to reduce the file size and increase speed. Because architects provide the same file to every project stakeholder, the data is massive because it may include furniture, trees, and other elements that building services engineers do not require. In terms of the thermal model used for heat loss and cooling calculations Plancal nova can build upon DWG/DXF files, but also on IFC models and qualify these for thermal calculations. It turned out the conversion of existing BIM models from third party project stakeholders into thermal models comes with a number of issues, mainly deriving from unaligned work flows between architects and MEP designers, improper work, or unfamiliarity with the requirement of BIM processes. We found the solution in a selective import of “intelligent” parts of the model, as well as a simplified 3D geometry-only import, without metadata. This allows customers to have a proper model even if there are errors in its structure and then quickly build a thermal model on top of it themselves.

Requirements of the software

From the findings we derived from the cooperation with our clients, we can conclude the following requirements for a BIM software: There should be an option to import the entire building as a thermal model. In addition it should be possible to exclusively import the entire building as 3D geometry only, without meta-data, with a proper and detailed representation of the geometry. There should be an option to exclusively import specific storeys. There should be a function to remove IFC classes from the BIM model that are not desired

Implementation of the requirements

After carefully considering the findings and conclusions we defined the implementation as below. The import of the thermal model directly from an IFC file happens within Plancal nova. To keep the data model consistent, the entire building is imported. Whenever possible and available, technical parameters and general information (such as room numbers and names) are imported too. In addition we created a new tool: The nova BIM Converter helps us to import the building as 3D geometry only. During the import users can remove storeys (e.g. ceiling voids defined as a separate floor) and IFC classes (e.g. furniture) to make sure they are not being used any further. Therefore only useful data is being imported which results in smaller file sizes and increases speed. The number and heights of stories can be manipulated. Especially if architects did not define floors properly, or added too many, this is a very useful tool to correct the model. in order to spot differences between files from different stages, models can be forced to be displayed in a single colour only. Referencing both models to each other makes it very simple to compare them floor by floor which has proven easier than comparing two models in 3D where all floors are visible at the same time, as this carries too much information at once. A special highlight is the development of an additional feature targeted for a better understanding and analysis of floor plans. The nova BIM Converter can display a model either with all 3D geometry details in a storey plan view, or simplify the representation of the objects as a 2D alike object. This means walls receive hatchings and doors are shown as in DWG files as a quadrant. This makes it easier to understand the room layouts. The geometry of this 3D model and its resulting floor plans are then available within Plancal nova and can be used to draw upon, whether it’s to plan and coordinate MEP components, or to create a thermal model for heat loss and cooling calculations.

Conclusion:

Within a planning process it’s important to not only consider the first import of a BIM model for the MEP designer, but also the repeating supply of building containing modifications. The work flow and software tools must support the CAD side as well as the thermal model of the project as best as possible.